Fan housing



June 16, 1953 w. R. HEATH 2,642,219

FAN HOUSING Filed June 12, 1948 2 Sheets-Sheet 1 INVENTOR. (11/7/1202;6. Heat/z ATTORNEYS.

June 16, 1953 w. R. HEATH v FAN HOUSING Filed June 12, 1948 2Sheets$heet 2 ATTORN EYS.

- casing.

Patented June 16 1953 UNITED STATES PATENT OFFICE- FAN HOUSING WilliamR. Heath, Buffalo, N. asslgnor to Buffalo Forge Company, Buffalo, N. Y.,a corporation of New York Application June 12, 1948, Serial No. 32,555

My invention relates in general to fan housings, and in particular toscroll-shaped housing for use in blower fans or pumps of the centrifugaltype.

As is Well known to those skilled in the art,the scroll-shaped casing ofa centrifugal blower fan not only acts as a collector to gather thefluid leaving the impeller of the fan and to conduct it to a centralpoint where it may be easily fed into a conventional pipe or duct, butalso serves to act as a difiuser to convert the kinetic energy in r thefluid, in the form of high velocity leaving the a useful terminalvelocity. This result may be accomplished by extending the dischargeduct a considerable distance beyond the main body'of the casing. Anotherway of achieving this result,

, in cases where space and cost are to be considered, it to provide thehousing with an outwardly flaring discharge duct which is connected toan outlet duct larger in size than the regular outlet of the A similarresult is accomplished by attaching the outlet of the housing to a ductlarger in size'than the outlet discharge opening.

When'it is attempted to accomplish .the above results by either anextended or an enlarged outlet cluct, some of the kinetic energyisconverted into potential energy in the duct, but at reduced efliciency.When, however, the flaring outlet is used, there is little or noconversion of energy and the efliciency of the fan is correspondinglyreduced. A further disadvantage of the use of the flaring dischargeduct'is that the fluid is forced to the outer surface of the duct bycentrifugal force, and this condition is aggravated when the fan isthrottled below a definite minimum value of delivery relative to thespeed of the fan.

It i well known that the velocity of the fluid leaving the impeller of acentrifugal blower or pump varies with the amount of resistance in thesystem supplied by the pump or fan so that the scroll-shaped housing isonly theoretically correct for a narrow range of fluid delivery relativeto the speed of rotation of the blower wheel. When the fan is throttledbelow this theoretically correct point, the scroll is larger than thatrequired for eificient operation. With certain impeller 6 Claims. (Cl.230-128) designs, it frequently happens that appreciable energyconversion is obtained above certain fluid deliveries when the fluidfills the outlet, but little conversion is obtained with slightly lessdelivery when the fluid does not fill the outlet. The point where thefluid flow changes is not clearly defined but varies with slight changesin flow conditions so that the entire output of the fan becomesunstable.

Numerous attempts have been made heretofore to overcome the abovedisadvantages and various expedients have been employed, uch asdeflectors located in the outlet of the casing and positioned as todirect the air toward the center of the outlet. When such deflectors arefixed in position, the capacity of the fan is thereby reduced; and, ifit is attempted to overcome this disadvantage by making the deflectorsadjustable, then the deflectors must be adjusted for each operatingcondition to which the fan is subjected in order to bring aboutefliciencyof operation. Moreover,

other disadvantages of the use of such deflectors are that undesirablenoises are created and the deflectors must be detached and removed fromthe housing when the wheel of the fan i to be removed through thedischarge opening thereof.

In carrying outmy invention, it is a principal object to produce ablower fan having a housing so designed that the disadvantages abovepointed out may be overcome, and one in which the maximum amount ofkinetic energy in the fluid may be converted into potential energy atthe outlet or discharge opening of the fan.

Another object is to provide a blower housing so formed that high.fan'eirlgciencies may be achieved, 'while at the sametime bringingabout a reduction in the cost of manufacture of the fan and the spaceoccupied thereby.

A further object is to provide a fan housing of scroll-shape which willembody all of the advantages of my invention, and at the same time havea discharge, openingso proportioned that the fan wheel of the blowermaybe removed therethrough;

A further object is to provide a housing for a blower fan having anoutlet passageway so formed as to direct the moving fluid toward thecenter of the opening.

Moreover, by means of my invention, a stable operation of my fan isassured when operating under varying delivery conditions and Where attimes the blower is throttled down with a consequent minimum value ofdelivery relative to wheel speed.

The above objects and advantages have been accomplished by the deviceshown in the accompanying drawings, of which:

Fig. I is a front elevational view of a blower fan embodying myinvention; and

Fig. 2 is a side elevation of the fan with a portion of the casingbroken away.

My blower fan comprises a housing IU of usual scroll-shape having sidewalls II and I2 connected together by the scroll-shaped outer wall Thehousing is supported in operable position by any suitable means, and forconvenience of illustration I have shown two pedestals l4; one securedto each of the side walls H and [2 by any suitable means. formed with abase flange l5 and with an upper flange IS. The flanges 16 of thepedestals support the bearings 20 within which the wheel shaft 2! of thedevice is rotatably mounted. The shaft 21 carries the wheel 22 of theblower fan. This wheel. may be any one of a number of different typesand comprising general, a plurality of blades. 23 atv each side of whichis provided a shroudring 25. The blades 23 are preferably secured. attheir inner ends to a wheel hub 25 which in turn is mounted upon theshaft 2 i.

In carrying out my invention, I have shown it as applied to a doubleinlet fan. Each of. the walls II and [2 of the housing is thereforeprovided withv an inlet eye opposite each end of the fan wheel 22. As iscustomary, each of these eyes is flared. inwardly and is of a diameterpreferably slightly less than the diameter ofthe opening of the adjacentshroud ring 25; of the wheel. The housing is also formed with the usualdischarge collar 31 which forms the discharge opening 32 of the fan. Thehousing is provided with a short neck rectangular. in cross sectionwhich. is located between a short discharge collar' and. the inner andouter ends of the scrollshaped outer wall, and serves to join thesecasing parts. The top part of the neck is formed with. an.inwardly-bowed portion. 33 ofv continuous curvilinear contour. which isconnected to the outer end of the outer wall l3=in tangential manner.forming av streamlined surface which. avoids ."the formation of. eddies.in the discharge collar 3] and the discharge duct (not shown) to whichthe collar is connected This inwardly-bowed portion serves to directtheair toward the. center.

of the opening and. immediately thereafter to expand it into the collar.The bottom wall of the neck is also provided at the housing cutoff withan inwardly-bowed portion 34 also of'continuous curvilinear contour.These'oppositely arrangedv inwardly-bowed portions which aresubstantially" flat in. lateral cross section serve to streamline thedischarge opening of the housing, and to project' the air stream fromopposite sides of the opening in jet-like manner toward the center ofthehousing outlet" and to immediately expand it outwardly in substantiallyuniform manner'in the: short collar and thereby to substantially fillthe collar upon entrance of the air stream therei in, thus preventingthe formation of eddies,

ergy within the housing, In of the fan. without Each pedestal ispreferably the necessity of an extended outlet duct or an outwardlyflaring nozzle. By streamlining the passageway leading to the dischargeopening 32, the stream is thereby nozzled down and permitted to expandsmoothly in two directions, thus enabling even small quantities of airto fill the discharge collar. This centering action is advantageousunder substantially all conditions of fan performance, but isparticularly advantageous when the fan is operating at a minimum valueof delivery relative to the speed of rotation of the fan wheel. Myinvention eliminates substantially all unstability occurring in blowerfans resulting from the use of straight-sided discharge ducts especiallythose operating under the above mentioned conditions.

While I have shown my invention as applied to a blower fan having twoinlet eyes, it is obvious that similar advantages may be achieved whenmy invention is used in connection with fans having buta single eye.

What is claimed is:

1. A housing for a blower device having. a

scroll-shaped outer wall, substantially flat side walls joining theouter wall, a fan wheel rotat ably mounted within the housing, adischarge collar provided at the outlet end of the housing forattachment to a discharge duct, an inwardlybowed curved portion attheouter end of the outer end of the outer wall, the curved. portionforming a part of a constricted. neck located between the collar and theouter wall, the neck being relatively short with respect to the lengthof the. outer wall, the inwardly-bowed wall portion curving inwardly intangential manner from the scroll-shaped wall and thence outwardly tothe collar in substantially one continuous smooth curved contour todirect the air. stream initially toward the center of the neck andthereafter to expand it outwardly into. the collar by reason of thecurved streamline contour of the neck to" substantially fill the collarimmediately upon entrance of the air stream therein, thus preventing theformation of eddy currents.

2. The combination according to claim 1 wherein the neck and the collarthroughout their length are of greater dimension in oross section thanthe diameter of the fan wheel to enablethe mounting and dismounting ofthe wheel there- I through.

31A. housing for a blower device having a scroll-shaped outer wall,substantially flat side walls joining the outerfwall, a fan wheelrotatably mounted within the housing, a discharge collar 1 provided atthe'outleti end of the housing forattachment to a discharge duct, aninwardlybowed curved. portion at the outer end of the outer wall, aninwardly bowed curvedp'ortion at theinner end of the outer wall, formingthe 1 housing cutofi, the inwardly-bowed portions being oppositelyarranged and forminga restricted neck joining thescroll-shaped outerwallto the collar,- said neck being relatively short with re- 1 spect'to:thel'ength of the outer-wall, the inwarddiately upon. the entrance ofsaidair stream therein, thus preventing the.

formation of eddy currents. v

I 4. The combination according to claim 3, wherein the cutoff is solocated that the center line of the fan wheel which lies in a planesubstantially parallel to the axis of the outlet is disposed between thesaid cutoff and the outer end of the wall oppositely thereto, and thedistance between the oppositely arranged inwardly-bowed portions beinggreater than the diameter of the fan wheel to enable the mounting anddismounting of the wheel therebetween.

5. A housing for a blower device having a scroll-shaped outer wall,substantially flat side walls joining the outer wall, a fan wheelrotatably mounted within the housing, a discharge collar provided at theoutlet end of the housing for attachment to a discharge duct, aninwardlybowed curved portion at the outer end of the outer Wall, thelength of the collar being less than the length of the inwardly-bowedportion, the curved portion forming a part'of a constriated neck locatedbetween the collar and the outer wall, the neck being relatively shortwith respect to the length of the outer wall, the inwardly-bowed wallportion curving inwardly in tangential manner from the scroll-shapedwall and thence outwardly to the collar in substantially one continuoussmooth curved contour to direct the air stream initially toward thecenter of the neck and thereafter to expand it outward-- ly into thecollar by reason of the curved streamline contour of the neck tosubstantially fill the collar immediately upon entrance of the airstream therein, thus preventing the formation of eddy currents.

6. A housing for a blower device having a scroll-shaped outer wall,substantially fiat side walls joining the outer Wall, a fan wheelrotatably mounted within the housing, a discharge collar provided at theoutlet end of the housing for attachment to a discharge duct, aninwardthe outer wall, the inwardly-bowed portions curving inwardly intangential manner from the scroll-shaped wall and thence outwardly tothe collar each in substantially one continuous I smooth curved contourto direct the air stream initially toward the center of the neck andthere- 1 after to expand it outwardly into the collar by reason of thecurved streamline contour of the neck to substantially fill the collarimmediately upon entrance of said air stream, thus preventing theformation of eddy currents.

WILLIAM R. HEATH. 1

References Cited in the file of this patent UNITED'STATES PATENTS NumberName Date 1,750,681 Morse Mar. 18, 1930 1,787,653 Anderson Jan. 6, 19311,914,919 Heermans June 20, 1933 FOREIGN PATENTS Number Country Date318,601 France July 1, 1902

